Senior Software Engineer (West Coast USA)

MISUMI Americas is hiring a Senior Backend Engineer to build and scale the backend systems for its instant quoting platform. The role focuses on costing, pricing, lead-time, and design-for-manufacturability services, while improving reliability and using AI coding agents in development.

Responsibilities:

• Design and develop highly available, scalable backend services in AWS
• Build and maintain event-driven, asynchronous systems using Node.js
• Create robust APIs (REST / GraphQL) powering customer-facing and internal tools
• Use AI coding agents to take features from design through implementation and testing, while owning the correctness of every change
• Write specs, tests, and repo context that make agent-driven development reliable in a large, established codebase
• Partner closely with product, frontend, and infrastructure teams to ship features that actually move the business
• Contribute to technical design discussions and drive best practices across the team
• Help shape how the team works with AI: sharing patterns, tooling, and lessons learned
• Debug production issues and improve system reliability
• Continuously improve code quality through testing, observability, and documentation

Requirements:

• 5 + years of backend engineering experience
• Strong skills in Node.js, JavaScript/TypeScript
• Experience building systems on AWS (SQS, Lambda, EC2, RDS, etc.)
• Solid understanding of distributed systems and event-driven architectures
• Experience designing and maintaining REST or GraphQL APIs
• Familiarity with SQL and NoSQL databases
• A commitment to writing unit and integration tests
• Knowledge of system design, caching, and security best practices (OWASP Top 10)
• Hands-on experience shipping production code with AI coding agents (e.g., Claude Code, Cursor, Copilot agent mode), with clear examples of where you had to step in, correct, or override them
• Strong code review skills, applied just as rigorously to AI-generated changes
• Must be a U.S. citizen or lawful permanent resident (green card holder)
• You take ownership and ship clean, maintainable, production-ready code
• You treat AI as a force multiplier, not a substitute for understanding the system
• You communicate clearly and collaborate across teams
• You solve problems proactively, even outside your immediate scope
• You enjoy mentoring others and raising the bar for engineering excellence
• You stay curious and keep learning new technologies and patterns
• AWS certification
• Experience with high-scale or business-critical systems
• Experience with pricing, quoting, or other numerically sensitive business logic
• Experience building agent workflows, custom tools, or MCP integrations for your team